Mollisina rubi blight

Mollisina rubi is a fungal pathogen that specifically targets blackberry plants, causing a type of leaf spot disease. Although it may seem secondary to more common blights, this fungus significantly impacts the plant's health by reducing leaf area and inducing premature senescence of the foliage.

The host range is primarily limited to species of the Rubus genus. Mollisina rubi tends to colonize older, lower leaves first, but in conditions of high humidity, it can quickly spread throughout the entire canopy, particularly in dense, poorly managed blackberry patches where air circulation is restricted.

The visual symptoms typically appear as circular, light-colored necrotic lesions on the leaves. As the infection progresses, a distinct dark brown or purple margin often develops around the spot. Eventually, tiny, disc-like fruiting bodies (apothecia) appear in the center of the necrotic tissue, signaling the maturation of the fungus.

The spread of this pathogen is heavily dependent on moisture. Rain splash and high humidity facilitate the dispersal of spores from the soil and decaying plant debris onto the leaves. The fungus overwinters in dead leaves, making the spring season a critical time for primary infection if sanitary measures are ignored.

Effective management strategies for Mollisina rubi revolve around cultural practices and timely chemical intervention:

• Strict sanitation: rake and remove all fallen leaves during late autumn to eliminate the primary overwintering source.
• Pruning: thin out canes to ensure adequate airflow and sunlight penetration within the canopy.
• Fungicide application: utilize preventative sprays before the rainy season if the infection history in the area is known.
• Site selection: choose well-drained locations to avoid microclimates with excessive humidity.